I run a 100 amp alternator mounted the same way. Extreme RPMs over 6000 to 9000 I shut the alternator off. Otherwise it works perfect. No assumptions here I ran this for many many years using the power steering bracket for the mount.
I needed to put a metric nut on the bracket to use the correct diameter bolt for the GM alternator to keep it straight.
Over 8000 it would throw the belt if charging, But like I said I had it on a switch with a constant close starter relay . I seen it go to 9300 I opened the hood to look and see if it threw the belt and to my surprise it was still on